Coal mine ventilation air methane oxidation power plant hot air recycling pipeline anti-backflow anti-coal dust explosion device

Abstract

The application discloses a coal mine ventilation air oxidation power plant hot air recycling pipeline anti-backflow and coal dust explosion prevention device, ventilation air of a coal mine is connected to a mixing device through a ventilation air shaft and a ventilation air guide channel, low-concentration gas enters the mixing device through a gas conveying pipeline, and the ventilation air and the low-concentration gas are mixed in the mixing device; the mixing device is connected to a regenerative oxidation device through an air inlet pipeline, high-temperature flue gas generated by the regenerative oxidation device is connected to a generator set through an air outlet pipeline, low-temperature flue gas generated by the regenerative oxidation device is connected to a chimney and a hot air recycling pipeline respectively, and a hot air fan conveys the low-temperature flue gas to the ventilation air guide channel; a PLC control system comprises an air flow monitoring part and a linkage shutdown anti-backflow and explosion prevention part. The device can realize linkage of the hot air fan and the regenerative oxidation device, and can cool the hot air fan after an emergency stop; and the device can also be used for preventing ventilation air carrying coal dust from flowing back into the hot air recycling pipeline, and essentially solves the problem of explosion source of a hot air recycling system.

Description

Technical Field

[0001] This invention relates to a backflow prevention and coal dust explosion prevention device for hot air reuse pipelines in coal mine waste heat oxidation power plants, belonging to the field of waste heat energy-saving technology safety assurance. Background Technology

[0002] Exhaust gas refers to the mixture of methane gas carried by ventilation after passing through coal mine working faces and other ventilation locations. It contains approximately 90% of the total methane emissions from coal mines in my country and has enormous potential for development and utilization. Due to its extremely low methane concentration, exhaust gas cannot be directly utilized. Currently, its development and utilization are mainly achieved through regenerative thermal oxidation technology.

[0003] Regenerative thermal oxidation (RTO) technology involves mixing exhaust gas with low-concentration methane gas and then conducting an oxidation reaction within a RTO unit to release heat. The resulting high-temperature flue gas (approximately 1000°C) is used to heat a boiler for steam power generation. However, RTO also generates significant amounts of low-temperature flue gas (approximately 150°C) that cannot be used in production processes, and long-term emissions of this low-temperature gas exacerbate the greenhouse effect. Some exhaust gas RTO power plants recycle this low-temperature flue gas, using hot air fans to transport it to the exhaust gas duct, achieving heat exchange between the exhaust gas (at ambient temperature) and the low-temperature flue gas. This technology not only maximizes the utilization of the waste heat from the low-temperature flue gas but also improves the heat exchange efficiency of the RTO unit, while reducing exhaust gas humidity and ensuring the sensitivity of concentration sensors.

[0004] Currently, there is a technology for low-temperature flue gas recycling, namely Chinese patent CN110145867A, which discloses "a coal mine shaft cascade heating system and operation method based on low-concentration gas oxidation". This system uses multi-stage heat exchangers to heat the air in the shaft, i.e., the exhaust air duct, by utilizing the waste heat of medium and low-quality flue gas, thus achieving cascade utilization of the waste heat. Another technology, Chinese patent CN114543109A, discloses "a gas heat storage oxidation molten salt heat storage peak-shaving system for coal mine shaft heating". This system stores the heat in the flue gas generated by low-concentration gas oxidation through molten salt heat storage units and transports it to the shaft, i.e., the exhaust air duct, through a heat exchanger for antifreeze, thereby achieving "peak shaving and valley filling" of the day and night heat load and meeting the heating demand throughout the day. However, none of the aforementioned patents considered the implementation of a linkage system between the regenerative thermal oxidizer and the hot air blower, nor the design of anti-backflow and explosion-proof devices in the hot air reuse pipeline. This could lead to a situation where, after the regenerative thermal oxidizer shuts down due to excessive concentration, the airflow in the hot air reuse pipeline and the exhaust air duct might reverse, causing the coal dust accumulated on the inner wall of the pipeline to be stirred up. The resulting coal dust cloud could then flow back to the higher-temperature hot air blower through the "chimney effect," triggering a coal dust explosion. Currently, there is a lack of anti-backflow and anti-coal dust explosion devices for hot air reuse pipelines in coal mine exhaust air oxidation power plants in China, and there is also a lack of linkage systems between the regenerative thermal oxidizer and the hot air blower. Summary of the Invention

[0005] To better address the aforementioned problems, this invention aims to provide a backflow prevention and coal dust explosion prevention device and method for using hot air reuse pipelines in coal mine exhaust gas oxidation power plants. This device enables the linkage between the hot air blower and the regenerative oxidation unit, and cools the hot air blower after an emergency stop. This device can also be used to prevent exhaust gas from carrying coal dust backflow into the hot air reuse pipeline, fundamentally solving the problem of explosion sources in hot air reuse systems.

[0006] The device provided by this invention utilizes a PLC control system to achieve linkage between the hot air blower and the regenerative oxidation device, and uses a fine water mist / liquid CO2 generator to cool the hot air blower after an emergency stop. The device also incorporates a check valve to prevent exhaust air carrying coal dust from flowing back into the hot air reuse pipeline, fundamentally solving the problem of explosion sources in the hot air reuse system.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A device for preventing backflow and coal dust explosion in a hot air reuse pipeline of a coal mine exhaust air oxidation power plant includes an exhaust air intake channel, a gas conveying pipeline, a mixing device, a regenerative oxidation device, a chimney, a hot air reuse pipeline, a fine water mist / liquid CO2 generator, and a PLC control system.

[0009] The exhaust air from the coal mine is connected to the blending device through the return air shaft and the exhaust air intake channel. Low-concentration methane enters the blending device through the methane conveying pipeline. The exhaust air from the coal mine and the low-concentration methane are mixed in the blending device.

[0010] The mixing device is connected to the regenerative oxidation device through the air inlet pipe. The high-temperature flue gas generated by the regenerative oxidation device is connected to the generator set through the air outlet pipe. At the same time, the low-temperature flue gas generated by the regenerative oxidation device is connected to the chimney and the hot air recycling pipe through the low-temperature flue gas outlet pipe respectively. The hot air fan transports the low-temperature flue gas to the exhaust air duct through the hot air recycling pipe.

[0011] The PLC control system includes an airflow monitoring section and an linkage shutdown anti-backflow and explosion-proof section. Specifically, the PLC control system includes a controller, a communication module, a storage module, and an equipment drive module. After the communication module receives the sensor response signal, the controller performs logical judgment, performs analog-to-digital conversion, and outputs the corresponding control signal to the equipment drive module to control the valve to open or close and adjust the speed of the hot air fan. At the same time, the storage module records the system's operating status.

[0012] The airflow monitoring section includes: a hot air fan, a first temperature sensor, a second temperature sensor, and a flow sensor; the second temperature sensor is installed on the hot air fan, and the first temperature sensor is installed in the exhaust air duct to monitor the airflow temperature; the flow sensor is installed in the exhaust air duct to monitor the airflow flow rate; all the above sensors are connected to the communication module of the PLC control system, which can promptly know the pipe temperature and flow rate; the communication module of the PLC control system is connected to control the hot air fan and can adjust the speed of the hot air fan.

[0013] The linked shutdown anti-backflow and explosion-proof components include: a check valve, a waste air vent pipe, a bypass valve, and a pneumatic quick-closing valve; the equipment drive module of the PLC control system is connected to control the fine water mist / liquid CO2 generator, and can control the start or stop of the fine water mist / liquid CO2 generator; the equipment drive module of the PLC control system is connected to control the bypass valve and the pneumatic quick-closing valve, and can control the opening or closing of the bypass valve and the pneumatic quick-closing valve; the regenerative oxidation device is connected to the communication module of the PLC control system, and the PLC controls... The system can know its operating status; the check valve is installed on the hot air reuse pipeline between the hot air blower and the exhaust air duct. This valve has one-way flow and can prevent the airflow carrying coal dust back into the hot air reuse pipeline and thus contacting the ignition source; the exhaust air vent pipe is set on the pipeline branch between the exhaust air duct and the blending device, and a bypass valve is installed on the branch to control the opening and closing of the exhaust air vent pipe; the pneumatic quick shut-off valve is set on the pipeline connecting the exhaust air duct and the blending device to control the exhaust air entering the blending device.

[0014] Preferably, the first temperature sensor in the exhaust air duct is installed near the outlet of the hot air reuse pipe, and its position is in the interval between the outlet of the hot air reuse pipe and the exhaust air vent pipe, so as to monitor the temperature of the airflow in the exhaust air duct after heating.

[0015] Preferably, the flow sensor in the exhaust air duct is installed near the outlet of the hot air reuse pipe, and its position is in the interval between the outlet of the hot air reuse pipe and the exhaust air vent pipe, so as to monitor the airflow in the exhaust air duct.

[0016] Preferably, the pneumatic quick-closing valve is normally open during normal operation and will automatically close in case of power failure in an emergency; the bypass valve is normally closed during normal operation and will automatically open in case of power failure in an emergency.

[0017] Preferably, the inlet end of the check valve is located at the end of the hot air reuse pipe near the hot air fan, and the outlet end is located near the exhaust air duct.

[0018] Preferably, the PLC control system further includes an audible and visual alarm device, including a display screen and a voice module, to prompt the operator to intervene manually.

[0019] Preferably, each oxidation generator set in the regenerative oxidation device is equipped with an intake-type induced draft fan.

[0020] Preferably, the temperature sensor should be a high-temperature thermocouple type or a resistance temperature sensor.

[0021] Preferably, the check valve, bypass valve, and pneumatic quick shut-off valve should have high temperature resistance (≥200℃).

[0022] The present invention also provides a method for using the above-mentioned anti-backflow and anti-explosion device for gas transmission pipelines in coal mine exhaust gas oxidation power plants, comprising the following steps:

[0023] (1) The coal mine exhaust air is connected to the blending device through the return air shaft and exhaust air duct. Low-concentration gas enters the blending device through the gas conveying pipeline. The coal mine exhaust air and low-concentration gas are mixed in the blending device until the gas concentration is 0.27% to 1.2%. Then, it is transported to the regenerative oxidation device to undergo oxidation reaction. The high-temperature flue gas generated by the regenerative oxidation device is transported to the generator set through the pipeline. The low-temperature flue gas generated is heated by the hot air blower through the low-temperature flue gas outlet pipe and the airflow in the exhaust air duct through the hot air recycling pipe. The remaining flue gas exceeding the rated air volume of the hot air blower is discharged into the atmosphere through the chimney.

[0024] (2) When the regenerative oxidation device is working normally, the PLC control system controls the hot air fan to work normally. At the same time, the PLC control system monitors the temperature of the hot air fan and the exhaust air duct in real time through the second temperature sensor and the first temperature sensor respectively. When the real-time temperature exceeds the preset value, the PLC control system activates the audible and visual alarm device to prompt the operator to intervene. The PLC control system monitors the airflow in the exhaust air duct in real time through the flow sensor. When the real-time flow exceeds or falls below the preset range value, the PLC control system controls the hot air fan to appropriately increase or decrease the speed to keep the airflow pressure in the exhaust air duct and the hot air return pipe in a relatively balanced state and prevent backflow.

[0025] (3) When the concentration of the regenerative oxidation unit exceeds the limit or the unit is shut down for maintenance, the PLC control system quickly cuts off the power supply to the hot air blower, opens the bypass valve and closes the pneumatic quick shut-off valve. The exhaust air in the exhaust air duct is discharged through the exhaust air vent pipe through the "chimney effect", preventing the exhaust air from continuously entering the blending unit and preventing the hot air from forming a backflow in the exhaust air duct, causing the coal dust accumulated on the inner wall of the pipe to rise and form a coal dust cloud. After the hot air blower stops, due to the one-way flow of the check valve, the check valve closes when there is no hot air blowing out, and the exhaust air duct is closed. Exhaust air cannot enter the hot air reuse duct through this valve, preventing airflow from flowing backward from the exhaust air intake channel into the hot air reuse duct, thus preventing coal dust cloud from flowing back and contacting the ignition source and causing a coal dust explosion; 1 second after the hot air fan power is cut off, the PLC control system activates the fine water mist / liquid CO2 generator to cool the hot air reuse duct and the hot air fan blades, thereby eliminating the ignition source; at the same time as cutting off the hot air fan power, the PLC control system activates the audible and visual alarm device to prompt the operator to intervene manually.

[0026] Preferably, before the regenerative oxidation device and hot air blower are in normal operation, the bypass valve and the fine water mist / liquid generator must be in the closed state, and the pneumatic quick shut-off valve must be in the open state.

[0027] Preferably, the hot air blower can only be turned on and operated when the regenerative oxidation device is in normal working order.

[0028] The beneficial effects of this invention are:

[0029] (1) The present invention has designed a safety device for hot air reuse pipeline, which can not only prevent the exhaust air from carrying coal dust backflow into the hot air reuse pipeline, thus avoiding the coal dust cloud from flowing back to the hot air blower at a higher temperature through the "chimney effect" and causing coal dust explosion, but also can monitor the airflow and temperature in the exhaust air duct in real time, and control the speed of the hot air blower to keep the airflow in the exhaust air duct within the set range, so that the airflow pressure in the exhaust air duct and the hot air reuse pipeline are in a relatively balanced state, preventing the phenomenon of airflow backflow.

[0030] (2) The present invention realizes real-time linkage between hot air blower and regenerative oxidation device through PLC control system. When the regenerative oxidation device stops, the power supply of hot air blower is quickly cut off and the exhaust pipe is opened at the same time to prevent the exhaust air duct from backflow and stirring up the coal dust accumulated on the inner wall of the pipe due to the shutdown of the regenerative oxidation device. In the event of daily concentration exceeding the limit or maintenance shutdown of the regenerative oxidation device in the exhaust air oxidation power plant, the pipeline safety is guaranteed, thereby realizing accident prevention and ensuring the safety of personnel. Attached Figure Description

[0031] Figure 1 This is a connection diagram of the device of the present invention;

[0032] Figure 2 This is a plan view of the device of the present invention;

[0033] Figure 3 This is a control flowchart of the device of the present invention;

[0034] In the diagram: 1-Return air shaft, 2-Exhaust air intake duct, 3-Mixing device, 4-Regenerative thermal oxidation device, 5-Fine water mist / liquid CO2 generator, 6-Hot air reuse duct, 7-Exhaust air exhaust duct, 8-Hot air fan, 9-Low temperature flue gas outlet duct, 10-PLC control system, 11-Chimney, 31-Pneumatic quick shut-off valve, 32-Check valve, 33-Bypass valve, 41-First temperature sensor, 42-Flow sensor, 43-Second temperature sensor. Detailed Implementation

[0035] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example

[0036] like Figures 1-2 As shown, a backflow prevention and coal dust explosion prevention device for hot air reuse pipeline in a coal mine exhaust air oxidation power plant includes an exhaust air intake channel 2, a gas transmission pipeline, a mixing device 3, a regenerative oxidation device 4, a chimney 11, a hot air reuse pipeline 6, a fine water mist / liquid CO2 generator 5, and a PLC control system 10.

[0037] The coal mine exhaust air is connected to the blending device 3 through the return air shaft 1 and the exhaust air duct 2. Low-concentration gas enters the blending device 3 through the gas conveying pipeline. The coal mine exhaust air and low-concentration gas are mixed in the blending device 3.

[0038] The mixing device 3 is connected to the regenerative oxidation device 4 through the air inlet pipe. The high-temperature flue gas generated by the regenerative oxidation device 4 is connected to the generator set through the air outlet pipe. At the same time, the low-temperature flue gas generated by the regenerative oxidation device is connected to the chimney 11 and the hot air recycling pipe 6 through the low-temperature flue gas outlet pipe 9. The hot air fan 8 transports the low-temperature flue gas to the exhaust air duct 2 through the hot air recycling pipe 6.

[0039] The PLC control system 10 includes an airflow monitoring section and an linkage shutdown anti-backflow and explosion-proof section.

[0040] The airflow monitoring section includes: a hot air fan 8, a first temperature sensor 41, a second temperature sensor 43, and a flow sensor 42; the second temperature sensor 43 is installed on the hot air fan 8, and the first temperature sensor 41 is installed in the exhaust air duct 2 to monitor the airflow temperature; the flow sensor 42 is installed in the exhaust air duct 2 to monitor the airflow rate; all the above sensors are connected to the PLC control system 10, which can promptly know the pipe temperature and flow rate; the PLC control system 10 is connected to control the hot air fan 8 and can adjust the fan speed of the hot air fan 8.

[0041] The linked shutdown anti-backflow and explosion-proof components include: a check valve 32, a waste air vent pipe 7, a bypass valve 33, and a pneumatic quick-stop valve 31; the PLC control system 10 is connected to control the fine water mist / liquid CO2 generator 5, and can control the start or stop of the fine water mist / liquid CO2 generator 5; the PLC control system 10 is connected to control the bypass valve 33 and the pneumatic quick-stop valve 31, and can control the opening or closing of the bypass valve 33 and the pneumatic quick-stop valve 31;

[0042] The regenerative thermal oxidation device 4 is connected to the PLC control system 10, which can immediately know the operating status of the device. The check valve 32 is installed on the hot air reuse pipe 6 between the hot air blower 8 and the exhaust air intake channel 2. This valve has one-way flow and can prevent the airflow carrying coal dust from flowing back into the hot air reuse pipe 6 and thus contacting the ignition source. The exhaust air vent pipe 7 is set on the pipeline branch between the exhaust air intake channel 2 and the blending device 3, and a bypass valve 33 is installed on the branch to control the opening and closing of the exhaust air vent pipe 7. The pneumatic quick shut-off valve 31 is set on the pipeline connecting the exhaust air intake channel 2 and the blending device 3 to control the exhaust air entering the blending device 3.

[0043] Preferably, the first temperature sensor 41 in the exhaust air duct 2 is installed near the outlet of the hot air return pipe 6, and its position is in the interval between the outlet of the hot air return pipe 6 and the exhaust air vent pipe 7, so as to monitor the temperature of the airflow in the exhaust air duct 2 after heating.

[0044] Preferably, the flow sensor 42 in the exhaust air duct 2 is installed near the outlet of the hot air reuse pipe 6, and its position is in the interval between the outlet of the hot air reuse pipe 6 and the exhaust air vent pipe 7, so as to monitor the airflow in the exhaust air duct 2.

[0045] Preferably, the pneumatic quick-stop valve 31 is normally open during normal operation and will automatically close in case of power failure in an emergency; the bypass valve 33 is normally closed during normal operation and will automatically open in case of power failure in an emergency.

[0046] Preferably, the inlet of the check valve 32 should be located at the end of the hot air return pipe 6 near the hot air fan 8, and the outlet should be located near the exhaust air duct.

[0047] Preferably, the PLC control system includes a controller, a communication module, a storage module, and a device drive module. After the communication module receives a sensor response signal, the controller performs logical judgment, performs analog-to-digital conversion, and outputs corresponding control signals to the device drive module to control the valve to open or close and adjust the speed of the hot air fan. Simultaneously, the storage module records the system's operational status. Further, the PLC control system 10 also includes an audible and visual alarm device, including a display screen and a voice module, to prompt the operator for manual intervention.

[0048] The present invention also provides a method for using the above-mentioned anti-backflow and anti-explosion device for gas transmission pipelines in coal mine exhaust gas oxidation power plants, comprising the following steps:

[0049] (1) The coal mine exhaust air is connected to the blending device 3 through the return air shaft 1 and the exhaust air intake channel 2. Low-concentration gas enters the blending device 3 through the gas conveying pipeline. The coal mine exhaust air and low-concentration gas are mixed in the blending device 3 until the gas concentration is about 1.2%, and then transported to the regenerative oxidation device 4 to undergo an oxidation reaction. The high-temperature flue gas generated by the regenerative oxidation device 4 is transported to the generator set through the pipeline. The low-temperature flue gas generated is heated by the hot air blower through the low-temperature flue gas outlet pipeline and the airflow in the exhaust air intake channel through the hot air recycling pipeline. The remaining flue gas exceeding the rated air volume of the hot air blower is discharged into the atmosphere through the chimney. In this embodiment, the rated air volume of the hot air blower is 2500 m³ / h. 3 / min.

[0050] (2) When the regenerative oxidation device 4 is working normally, the PLC control system 10 controls the hot air blower 8 to work normally. At the same time, the PLC control system 10 monitors the airflow temperature in the hot air blower 8 and the exhaust air duct 2 in real time through the second temperature sensor 43 and the first temperature sensor 41 respectively. When the real-time temperature exceeds the preset value, the PLC control system 10 activates the audible and visual alarm device to prompt the operator to intervene. The PLC control system 10 monitors the airflow in the exhaust air duct 2 in real time through the flow sensor 42. When the real-time flow exceeds or falls below the preset range value, the PLC control system 10 controls the hot air blower 8 to appropriately increase or decrease the speed so that the airflow pressure in the exhaust air duct 2 and the hot air return pipe 6 is in a relatively balanced state, preventing the backflow phenomenon.

[0051] (3) When the concentration of the regenerative oxidation device 4 exceeds the limit or is shut down for maintenance, the PLC control system 10 quickly cuts off the power to the hot air blower 8, opens the bypass valve 33 and closes the pneumatic quick shut-off valve 31. The exhaust air in the exhaust air duct 2 is discharged through the exhaust air vent pipe 7 through the "chimney effect", preventing the exhaust air from continuously entering the mixing device 3 and preventing the hot air from forming a backflow in the exhaust air duct 2, causing the coal dust accumulated on the inner wall of the pipe to rise and form a coal dust cloud. After the hot air blower 8 stops, due to the one-way flow of the check valve 32, the check valve closes when there is no hot air blowing out, and the exhaust air duct 2. Exhaust air cannot enter the hot air reuse duct 6 through this valve, preventing airflow from flowing backward from the exhaust air intake channel 2 into the hot air reuse duct 6, thus preventing coal dust cloud from flowing back and contacting the ignition source, causing a coal dust explosion; 1 second after the power to the hot air fan 8 is cut off, the PLC control system 10 activates the fine water mist / liquid CO2 generator 5 to cool the hot air reuse duct 6 and the fan blades of the hot air fan 8, thereby eliminating the ignition source; Simultaneously with cutting off the power to the hot air fan 8, the PLC control system 10 activates the audible and visual alarm device to prompt the operator to intervene manually. Figure 3 As shown.

[0052] Preferably, before the regenerative oxidation device 4 and the hot air blower 8 are in normal operation, the bypass valve 32 and the fine water mist / liquid CO2 generator 5 must be in the closed state, while the pneumatic quick shut-off valve 31 must be in the open state.

[0053] Preferably, the hot air blower 8 can only be turned on and operated when the regenerative oxidation device 4 is working normally.

[0054] The following describes the response steps of the linkage shutdown anti-backflow and anti-explosion part of the anti-backflow and anti-explosion device for the gas pipeline of the coal mine exhaust gas oxidation power plant of the present invention in a preferred embodiment:

[0055] S100, system power-on and initialization;

[0056] S200, the PLC control system checks whether the bypass valve and the fine water mist / liquid CO2 generator are in the closed state and whether the pneumatic quick shut-off valve is in the open state. If yes, it jumps to S300; if not, it jumps to S201.

[0057] S201, the hot air fan is in the off state, jump to S200;

[0058] S300: The PLC control system checks whether the regenerative oxidation device is working properly. If it is, it jumps to S400; otherwise, it jumps to S301.

[0059] S301, the PLC control system cuts off the power to the hot air blower, closes the pneumatic quick shut-off valve, opens the bypass valve, activates the audible and visual alarm device, and jumps to S302.

[0060] S302, 1 second after the hot air blower power is cut off, the PLC control system starts the fine water mist / liquid CO2 generator, closes the return air shaft, waits for manual takeover, and ends;

[0061] S400, the hot air fan is in normal working condition, jump to S300.

[0062] The following describes the response steps of the airflow monitoring section of the anti-backflow and anti-explosion device for the gas pipeline of the coal mine exhaust gas oxidation power plant of the present invention in a preferred embodiment:

[0063] S100, system power-on and initialization;

[0064] S200, the hot air blower is in normal working condition, while S300 and S400 are performed simultaneously;

[0065] S300, the PLC control system checks whether the airflow rate of the flow sensor in the exhaust air duct reaches the preset range value under the current operation of n units in the regenerative thermal oxidizer (RTO). If it has reached the preset range value, it jumps to S200; if it is higher than the preset range value, it jumps to S301; if it is lower than the preset range value, it jumps to S302.

[0066] Preset range value

[0067] In the above formula, f is the current frequency (Hz) of the fan of the selected regenerative thermal oxidizer model, F is the full-frequency (Hz) of the fan of the selected regenerative thermal oxidizer model, and Q RTO The rated air volume (m³) of a single fan for the selected regenerative thermal oxidation unit model. 3 / min), Q1 is the actual flow rate of the extraction pumping station (m³ / min). 3 / min), Q2 is the design flow limit of the central pump station (m³ / min). 3 / min), q is the flow rate reserved fluctuation range value (m 3 / min); in this embodiment, the rated air volume is 1500m³ / min. 3 / min;

[0068] S301, the PLC control system controls the hot air fan to appropriately increase its speed based on the difference between the preset range value and the actual value of the airflow, and then jumps to S300;

[0069] S302, the PLC control system controls the hot air fan to appropriately reduce its speed based on the difference between the preset range value and the actual value of the airflow, and jumps to S300;

[0070] S400, the PLC control system checks whether the airflow temperature of temperature sensor A in the exhaust air duct is within the preset value of 200℃. If it is within the preset value, it jumps to S200; if it is higher than the preset value, it jumps to S401.

[0071] S401, the PLC control system activates the audible and visual alarm device to prompt the operator to intervene manually, then ends.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for preventing backflow and coal dust explosion in a hot air reuse pipeline of a coal mine exhaust gas oxidation power plant, characterized in that: It includes exhaust air duct, gas transmission pipeline, mixing device, regenerative thermal oxidizer, chimney, hot air recycling pipeline, fine water mist / liquid CO2 generator, and PLC control system; The coal mine exhaust air is connected to the blending device through the return air shaft and exhaust air duct. Low-concentration methane enters the blending device through the methane conveying pipeline. The coal mine exhaust air and low-concentration methane are mixed in the blending device. The blending device is connected to the regenerative thermal oxidizer through the air inlet pipeline. The high-temperature flue gas generated by the regenerative thermal oxidizer is connected to the generator set through the air outlet pipeline. At the same time, the low-temperature flue gas generated by the regenerative thermal oxidizer is connected to the chimney and the hot air recycling pipeline through the low-temperature flue gas outlet pipeline. The hot air fan transports the low-temperature flue gas to the exhaust air duct through the hot air recycling pipeline. The PLC control system includes an airflow monitoring section and an linkage shutdown anti-backflow and explosion-proof section; specifically, the PLC control system includes a controller, a communication module, a storage module, and an equipment drive module; after the communication module receives the sensor response signal, the controller performs logical judgment, performs analog-to-digital conversion, and outputs the corresponding control signal to the equipment drive module to control the valve to open or close and adjust the speed of the hot air fan, while the storage module records the system's operating status. The airflow monitoring section includes: a hot air fan, a first temperature sensor, a second temperature sensor, and a flow sensor; the second temperature sensor is installed on the hot air fan, and the first temperature sensor is installed in the exhaust air duct to monitor the airflow temperature; the flow sensor is installed in the exhaust air duct to monitor the airflow flow rate; all the above sensors are connected to the communication module of the PLC control system, which can promptly know the pipe temperature and flow rate; the communication module of the PLC control system is connected to control the hot air fan and can adjust the hot air fan speed; The linked shutdown anti-backflow and explosion-proof components include: a check valve, a waste air vent pipe, a bypass valve, and a pneumatic quick-closing valve; the equipment drive module of the PLC control system is connected to control the fine water mist / liquid CO2 generator, controlling its start-up or shutdown; the equipment drive module of the PLC control system is connected to control the bypass valve and the pneumatic quick-closing valve, enabling control of their start-up or shutdown; the regenerative oxidation device is connected to the equipment drive module of the PLC control system, which controls its operating status; the check valve is installed on the hot air reuse pipe between the hot air fan and the waste air intake channel, and this valve has unidirectional flow, preventing the airflow carrying coal dust backflow into the hot air reuse pipe and thus contacting the ignition source; the waste air vent pipe is located on a branch line between the waste air intake channel and the blending device, and a bypass valve is installed on the branch line to control the opening and closing of the waste air vent pipe; the pneumatic quick-closing valve is located on the pipeline connecting the waste air intake channel and the blending device to control the waste air entering the blending device.

2. The anti-backflow and anti-coal dust explosion device for hot air reuse pipelines in coal mine exhaust gas oxidation power plants according to claim 1, characterized in that: The first temperature sensor in the exhaust air duct is installed near the outlet of the hot air reuse pipe, and its position is in the interval between the outlet of the hot air reuse pipe and the exhaust air vent pipe, to monitor the temperature of the airflow after heating in the exhaust air duct; the flow sensor in the exhaust air duct is installed near the outlet of the hot air reuse pipe, and its position is in the interval between the outlet of the hot air reuse pipe and the exhaust air vent pipe, to monitor the airflow rate in the exhaust air duct.

3. The anti-backflow and anti-coal dust explosion device for hot air reuse pipelines in coal mine exhaust gas oxidation power plants according to claim 1, characterized in that: The pneumatic quick-closing valve is normally open during operation and will automatically close in case of power failure in an emergency. The bypass valve is normally closed during operation and will automatically open in case of power failure in an emergency. The inlet of the check valve is located at the end of the hot air return pipeline near the hot air fan, and the outlet is located near the exhaust air duct. The check valve, bypass valve, and pneumatic quick-closing valve should be able to withstand high temperatures of ≥200℃.

4. The anti-backflow and anti-coal dust explosion device for hot air reuse pipelines in coal mine exhaust gas oxidation power plants according to claim 1, characterized in that: The PLC control system also includes an audible and visual alarm device, including a display screen and a voice module, to prompt operators to intervene manually.

5. The anti-backflow and anti-coal dust explosion device for hot air reuse pipelines in coal mine exhaust gas oxidation power plants according to claim 1, characterized in that: Each oxidation generator set in the regenerative oxidation device is equipped with an intake-type induced draft fan.

6. The anti-backflow and anti-coal dust explosion device for hot air reuse pipelines in coal mine exhaust gas oxidation power plants according to claim 1, characterized in that: The temperature sensor is selected from high-temperature thermocouple type or resistance temperature sensor.

7. A method of using the anti-backflow and anti-explosion device for gas transmission pipelines in coal mine exhaust gas oxidation power plants according to any one of claims 1 to 6, characterized in that... Includes the following steps: (1) The coal mine exhaust air is connected to the blending device through the return air shaft and exhaust air duct. Low-concentration gas enters the blending device through the gas conveying pipeline. The coal mine exhaust air and low-concentration gas are mixed in the blending device until the gas concentration is 0.27% to 1.2%. Then, it is transported to the regenerative oxidation device to undergo oxidation reaction. The high-temperature flue gas generated by the regenerative oxidation device is transported to the generator set through the pipeline. The low-temperature flue gas generated is heated by the hot air blower through the low-temperature flue gas outlet pipe and the airflow in the exhaust air duct through the hot air recycling pipe. The remaining flue gas exceeding the rated air volume of the hot air blower is discharged into the atmosphere through the chimney. (2) When the regenerative oxidation device is working normally, the PLC control system controls the hot air fan to work normally. At the same time, the PLC control system monitors the temperature of the hot air fan and the exhaust air duct in real time through the second temperature sensor and the first temperature sensor respectively. When the real-time temperature exceeds the preset value, the PLC control system activates the audible and visual alarm device to prompt the operator to intervene. The PLC control system monitors the airflow in the exhaust air duct in real time through the flow sensor. When the real-time flow exceeds or falls below the preset range value, the PLC control system controls the hot air fan to appropriately increase or decrease the speed to keep the airflow pressure in the exhaust air duct and the hot air return pipe in a relatively balanced state and prevent backflow. (3) When the concentration of the regenerative oxidation unit exceeds the limit or the unit is shut down for maintenance, the PLC control system quickly cuts off the power supply to the hot air blower, opens the bypass valve and closes the pneumatic quick shut-off valve. The exhaust air in the exhaust air duct is discharged through the exhaust air vent pipe by the "chimney effect", preventing the exhaust air from continuously entering the mixing unit and preventing the hot air from forming a backflow in the exhaust air duct, causing the coal dust accumulated on the inner wall of the pipe to be raised and forming a coal dust cloud. After the hot air blower stops, due to the one-way flow of the check valve, the check valve closes when there is no hot air blowing out, and the exhaust air duct is closed. Exhaust air cannot enter the hot air reuse duct through this valve, preventing airflow from flowing backward from the exhaust air intake channel into the hot air reuse duct, thus preventing coal dust cloud from flowing back and contacting the ignition source and causing a coal dust explosion; 1 second after the hot air fan power is cut off, the PLC control system activates the fine water mist / liquid CO2 generator to cool the hot air reuse duct and the hot air fan blades, thereby eliminating the ignition source; at the same time as cutting off the hot air fan power, the PLC control system activates the audible and visual alarm device to prompt the operator to intervene manually.

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